Voltage switching circuit

Abstract

The utility model discloses a voltage switching circuit, and relates to the circuit field, a first controllable switch, a first control module and a first unidirectional conduction module form a first voltage output loop, a second controllable switch, a second control module and a third controllable switch form a second voltage output loop, when the first voltage is conducted, the first unidirectional conduction module is switched on, and when the second voltage is switched on, the third controllable switch is switched off. When the first controllable switch is switched on, a first voltage is output from the cathode of the first one-way switch-on module; when the second voltage is switched on and the first voltage is not switched on, the second controllable switch and the third controllable switch are switched on, and the second voltage is output from the second end of the third controllable switch; the first voltage and the second voltage can be realized by flexibly accessing different types of power supply voltages according to application requirements, so that the flexibility is high, and the application range is wider; the first one-way conduction module and the third controllable switch are used for avoiding current backflow during first voltage output and second voltage output, reliable switching power supply is achieved, in addition, the whole circuit is achieved through discrete devices, and cost is low.

Description

Technical Field

[0001] This utility model relates to the field of circuits, and in particular to a voltage switching circuit. Background Technology

[0002] With the continuous development of power equipment, users have increasingly higher requirements for equipment reliability. Voltage switching circuits have gradually become an important component of power supply systems for equipment, especially for critical equipment. Voltage switching circuits can provide redundant power supplies, ensuring power continuity and preventing downtime or accidents caused by a single power supply failure. Therefore, how to implement a stable and reliable voltage switching circuit has become an urgent technical problem to be solved. Currently, traditional voltage switching circuits often use specialized power switching chips, along with peripheral circuits to achieve switching between different voltages. However, the functions of the power switching chips themselves are relatively fixed, resulting in poor flexibility and hindering widespread adoption of voltage switching circuits. Utility Model Content

[0003] The purpose of this invention is to provide a voltage switching circuit that is highly flexible and has a wider range of applications. It utilizes a first unidirectional conduction module and a third controllable switch to avoid current backflow when the first voltage output is used and the second voltage output is used, thus achieving reliable switching power supply. In addition, the entire circuit is implemented using discrete components, resulting in lower cost.

[0004] To solve the above-mentioned technical problems, this utility model provides a voltage switching circuit, comprising:

[0005] The first controllable switch has a first terminal for connecting to a first voltage and a second terminal for outputting the first voltage.

[0006] The first control module has an input terminal for receiving the first voltage and an output terminal connected to the control terminal of the first controllable switch. It is used to control the first controllable switch to be turned on when the first voltage is connected and to control the first controllable switch to be turned off when the first voltage is not connected.

[0007] The second controllable switch has a first terminal for connecting to the second voltage and a second terminal for outputting the second voltage.

[0008] The second control module has an input terminal for receiving the first voltage and the second voltage, and an output terminal connected to the control terminal of the second controllable switch. It is used to control the second controllable switch to be turned on when the second voltage is turned on and the first voltage is not turned on, and to control the second controllable switch to be turned off when the second voltage is not turned on or the first voltage is turned on.

[0009] Optional, also includes:

[0010] The first unidirectional conduction module has its anode connected to the second terminal of the first controllable switch, and its cathode serving as the output terminal of the first voltage.

[0011] And / or,

[0012] The third controllable switch has its control terminal connected to the anode of the first unidirectional conduction module and the second terminal of the first controllable switch, and its first terminal connected to the second terminal of the second controllable switch. The second terminal serves as the output terminal of the second voltage, and is used to turn off when the first voltage is turned on and turn on when the first voltage is not turned on.

[0013] Optional, also includes:

[0014] The first energy storage module has its input end connected to the output end of the second control module and its output end connected to the control end of the second controllable switch. It is used to discharge when switching from the second voltage output to the first voltage output, so as to control the second controllable switch to conduct for a first preset duration.

[0015] And / or,

[0016] The second energy storage module has its input terminal connected to the anode of the first unidirectional conduction module and the second terminal of the first controllable switch, respectively, and its output terminal connected to the control terminal of the third controllable switch. It is used to discharge when switching from the second voltage output to the first voltage output, so as to control the third controllable switch to conduct for a second preset duration.

[0017] Optionally, the first energy storage module includes:

[0018] The first energy storage resistor has its first end connected to the output end of the second control module;

[0019] The first energy storage capacitor has its first end grounded, and its second end connected to the second end of the first energy storage resistor and the control terminal of the second controllable switch, respectively.

[0020] Optional, also includes:

[0021] The first soft-start module has a first end connected to the first end of the first controllable switch and a second end connected to the control end of the first controllable switch.

[0022] And / or,

[0023] The second soft-start module has a first end connected to the first end of the second controllable switch and a second end connected to the control end of the second controllable switch.

[0024] Optional, also includes:

[0025] The DCDC module has its input terminal connected to the second terminal of the first controllable switch, and is used to convert the first voltage into a voltage of a preset value.

[0026] The first inductor has its first end connected to the positive output terminal of the DC-DC module;

[0027] The first capacitor has its first end connected to the second end of the first inductor, the anode of the first unidirectional conduction module, and the control terminal of the third controllable switch, respectively. Its second end is grounded and connected to the negative output terminal of the DC-DC module.

[0028] Optionally, it may also include one or more combinations of a first input capacitor, a second input capacitor, a first output capacitor, and a second output capacitor;

[0029] The first terminal of the first input capacitor is grounded, the second terminal is connected to the first voltage, and is connected to the first terminal of the first controllable switch;

[0030] The first terminal of the second input capacitor is grounded, the second terminal is connected to the second voltage, and is connected to the first terminal of the second controllable switch;

[0031] The first terminal of the first output capacitor is grounded, and the second terminal is connected to the cathode of the first unidirectional conduction module;

[0032] The first terminal of the second output capacitor is grounded, and the second terminal is connected to the second terminal of the third controllable switch.

[0033] Optionally, the first control module includes:

[0034] The first voltage divider circuit has its first terminal connected to the control terminal of the first controllable switch, and its voltage divider terminal connected to the first terminal of the first controllable switch.

[0035] The fourth controllable switch has a control terminal for connecting to the first voltage, a first terminal grounded, and a second terminal connected to the second terminal of the first voltage divider circuit. It is used to conduct when the first voltage is connected, so as to cooperate with the first voltage divider circuit to control the first controllable switch to conduct, and to turn off when the first voltage is not connected, so as to cooperate with the first voltage divider circuit to control the first controllable switch to turn off.

[0036] Optionally, the first control module further includes:

[0037] The second voltage divider circuit has a first terminal for connecting to the first voltage, a second terminal for grounding, and a voltage divider terminal connected to the control terminal of the fourth controllable switch.

[0038] And / or,

[0039] The first current limiting module has its first end connected to the output end of the second voltage divider circuit, and its second end connected to the control end of the fourth controllable switch.

[0040] Optionally, the second control module includes:

[0041] The second current limiting module has its first terminal used to connect to the second voltage.

[0042] The fifth controllable switch has a control terminal for connecting to the first voltage and a first terminal for grounding. It is used to turn on when the first voltage is connected and turn off when the first voltage is not connected.

[0043] The sixth controllable switch has its control terminal connected to the second terminal of the fifth controllable switch and connected to the second voltage. Its first terminal is grounded, and its second terminal is connected to the second terminal of the second current limiting module and the control terminal of the second controllable switch, respectively. It is used to turn off when the fifth controllable switch is on or when the second voltage is not connected, so as to control the second controllable switch to turn off. When the fifth controllable switch is off and the second voltage is connected, it is turned on, so as to control the second controllable switch to turn on.

[0044] Optionally, the second control module further includes:

[0045] The third voltage divider circuit has the second voltage connected to its first terminal, the control terminal of the sixth controllable switch connected to its second terminal, and the voltage divider terminal connected to the second terminal of the fifth controllable switch.

[0046] And / or,

[0047] The fourth voltage divider circuit has the first terminal connected to the first voltage, the second terminal grounded, and the voltage divider terminal connected to the control terminal of the fifth controllable switch.

[0048] This invention provides a voltage switching circuit, including a first controllable switch, a first control module, a first unidirectional conduction module, a second controllable switch, a second control module, and a third controllable switch. The first controllable switch, the first control module, and the first unidirectional conduction module constitute an output circuit for a first voltage, and the second controllable switch, the second control module, and the third controllable switch constitute an output circuit for a second voltage. When the first voltage is on, the first controllable switch is on, and the first voltage is output from the cathode of the first unidirectional conduction module. When the second voltage is on and the first voltage is not on, the second and third controllable switches are on, and the second voltage is output from the second terminal of the third controllable switch. The first and second voltages can be flexibly connected to different types of power supply voltages according to application requirements, which is highly flexible and has a wider range of applications. The first unidirectional conduction module and the third controllable switch are used to avoid current backflow when the first voltage is output and the second voltage is output, so as to achieve reliable power supply switching. In addition, the entire circuit is implemented with discrete components, which reduces costs. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 A schematic diagram of a voltage switching circuit provided by this utility model;

[0051] Figure 2 This is a schematic diagram of another voltage switching circuit provided by this utility model. Detailed Implementation

[0052] The core of this utility model is to provide a voltage switching circuit that is highly flexible and has a wider range of applications. It uses a first unidirectional conduction module and a third controllable switch to avoid current backflow when the first voltage output is used and the second voltage output is used to achieve reliable switching power supply. In addition, the entire circuit is implemented with discrete components, which reduces the cost.

[0053] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0054] Please refer to Figure 1 , Figure 1 This is a schematic diagram of a voltage switching circuit provided by this utility model; please refer to... Figure 2 , Figure 2 This is a schematic diagram of another voltage switching circuit provided by this utility model; wherein, POWER_1 is the first voltage, POWER_2 is the second voltage, and SYS_POWER is the final output voltage to the device. To solve the above technical problems, this utility model provides a voltage switching circuit, including:

[0055] The first controllable switch Q1 has a first terminal for connecting to a first voltage and a second terminal for outputting the first voltage.

[0056] The first control module 1 has an input terminal for receiving a first voltage and an output terminal connected to the control terminal of the first controllable switch Q1. It is used to control the first controllable switch Q1 to conduct when the first voltage is connected and to control the first controllable switch Q1 to turn off when the first voltage is not connected.

[0057] The second controllable switch Q2 has a first terminal for connecting to the second voltage and a second terminal for outputting the second voltage.

[0058] The second control module 2 has an input terminal for receiving the first voltage and the second voltage, and an output terminal connected to the control terminal of the second controllable switch Q2. It is used to control the second controllable switch Q2 to conduct when the second voltage is connected and the first voltage is not connected, and to control the second controllable switch Q2 to turn off when the second voltage is not connected or the first voltage is connected.

[0059] As an optional embodiment, it also includes:

[0060] The first unidirectional conduction module D1 has its anode connected to the second terminal of the first controllable switch Q1, and its cathode serving as the output terminal of the first voltage.

[0061] And / or,

[0062] The third controllable switch Q3 has its control terminal connected to the anode of the first unidirectional conduction module D1 and the second terminal of the first controllable switch Q1, respectively. Its first terminal is connected to the second terminal of the second controllable switch Q2. The second terminal serves as the output terminal of the second voltage, which is used to turn off when the first voltage is turned on and to turn on when the first voltage is not turned on.

[0063] It is easy to understand that, in order to achieve output voltage switching, the voltage switching circuit provided in this application is equipped with a first circuit for outputting a first voltage and a second circuit for outputting a second voltage. A first controllable switch Q1 is connected in series in the first circuit, and is turned on or off under the action of the first control module 1, thereby controlling whether the first voltage is output. A second controllable switch Q2 and a third controllable switch Q3 are connected in series in the second circuit. The second controllable switch Q2 is turned on or off under the action of the second control module 2, and the control terminal of the third controllable switch Q3 is connected to the output terminal of the first circuit, and is turned on or off under the action of the output terminal of the first circuit, thereby controlling whether the second voltage is output. The voltage switching circuit can be used for power supply switching in a power system. The output terminals of the first voltage and the second voltage are both connected to the power supply terminal of the equipment to be powered. The first voltage is the main power and the second voltage is the auxiliary power. When the first voltage and the second voltage are connected at the same time, the first voltage will be output first; that is, when both the first voltage and the second voltage can provide power, the first voltage will be used to power the equipment first. When the first voltage is applied, the first controllable switch Q1 is turned on, and the second control module 2 controls the second controllable switch Q2 to turn off. The first circuit can output the first voltage through the turned-on first controllable switch Q1. The output first voltage then controls the third controllable switch Q3 to turn off, ensuring the continuous disconnection of the second circuit. When the first voltage is not applied and the second voltage is applied, the first controllable switch Q1 is turned off, and the second controllable switch Q2 is turned on. The first circuit does not output the first voltage, and the third controllable switch Q3 can also remain on. The second circuit can output the second voltage through the turned-on second controllable switch Q2 and the third controllable switch Q3. Thus, the controllable switches are used to realize power switching and ensure the continuous output of voltage.

[0064] Understandably, the output of the first circuit is equipped with a first unidirectional conduction module D1, which serves to prevent reverse connection and specify the current direction. Simultaneously, the output of the second circuit is equipped with a third controllable switch Q3. When the first circuit outputs the first voltage, the third controllable switch Q3 is turned off, preventing the first voltage output to the device's power supply from flowing back into the second circuit through the turned-off switch. This also avoids leakage current affecting the second circuit, ensuring stable operation and allowing a stable switch from the first circuit to the second circuit when a second voltage is needed. When the second circuit outputs the second voltage, due to the protection of the first unidirectional conduction module D1, the second voltage output to the device's power supply cannot flow back into the first circuit through the reverse direction of the first unidirectional conduction module D1, ensuring stable operation of the first circuit. This also prevents backflow of voltage to the device's power supply during voltage switching, thus protecting the entire voltage switching circuit and preventing circuit damage.

[0065] It should be noted that this application does not specifically limit the specific types and implementation methods of the first controllable switch Q1, the first control module 1, the first unidirectional conduction module D1, the second controllable switch Q2, the second control module 2, and the third controllable switch Q3. The first controllable switch Q1, the second controllable switch Q2, and the third controllable switch Q3 can be implemented using power electronic switching transistors such as MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), IGBTs (Insulated-Gate Bipolar Transistors), and transistors. Figure 2 As shown, the first controllable switch Q1, the second controllable switch Q2, and the third controllable switch Q3 are all implemented using PMOS transistors. Alternatively, other types of controllable switches, such as relays, can be selected depending on the specific application. The first control module 1 and the second control module 2 can be implemented using circuits built with components such as MOSFETs, in conjunction with the selected controllable switches. The first unidirectional conduction module D1 can be implemented using diodes, thyristors, or other methods. The specific voltage values ​​and implementation methods of the first and second voltages can be selected and set according to the actual equipment requirements, using DC power supplies, AC power supplies, or other methods.

[0066] Furthermore, this application provides a voltage switching circuit using two voltage sources as an example. In practical applications, this circuit design can also be used to switch between multiple voltage sources. Specific circuit details and implementation methods will not be elaborated upon here. The voltage switching circuit can be applied not only in device power supply scenarios but also in other application scenarios where devices have different voltage requirements. This application does not impose any particular limitations on these applications.

[0067] As a specific implementation example, taking the application scenario of device power supply as an example, such as Figure 2As shown, the entire power supply system has two power supply modes: a first voltage POWER_1 power supply and a second voltage POWER_2 power supply. Initially, the power supply system is in a power-off state, and the fourth controllable switch Q4 in the first control module 1 is turned off, causing the first controllable switch Q1 to be in the off state. External main power POWER_1 is used as variable 1; VBUS power supply POWER_2 is used as variable 2. The voltage of POWER_1 is 12V, and the voltage of POWER_2 is 5V. The first circuit and the second circuit are switched through two connection points, A and B. The high potential state of point A is 12V, and the low potential state is 0V. The high potential state of point B is 5V, and the low potential state is 0V. SYS_POWER is the voltage of the device's power supply terminal. Here, it is assumed that the power supply voltage required by the device is 5V. The various operating states of the voltage switching circuit are described in detail below.

[0068] The first operating state is when the first voltage POWER_1 is connected and the second voltage POWER_2 is not connected. When POWER_1 is connected, the potential at point A is high. After the potential at point A is pulled high, it controls the fourth controllable switch Q4 in the first control module 1 to conduct, so that the second terminal of the first voltage divider circuit, that is, one end of the voltage divider resistor Rf2, is grounded. Therefore, the first current flow of POWER_1 at this time is: resistor Rf3 -> resistor Rx1 -> control terminal of the fourth controllable switch Q4. Simultaneously, after POWER_1 is connected, point A is at a high level (12V) after passing through the pre-amplifier circuit. The gate (G) of the fourth controllable switch Q4 receives the voltage after being divided by resistors Rf3 and Rf4, causing the fourth controllable switch Q4 to conduct and ground one end of the control resistor Rf2. The gate (G) of the first controllable switch Q1 is pulled low by the conducting fourth controllable switch Q4 after being divided by resistors Rf1 and Rf2, causing the first controllable switch Q1 to conduct. The current flows through the first controllable switch Q1 and the DC-DC module U1, outputting 5V, and then passes through the first inductor L1 and the first unidirectional conduction module D1 to be input to the device power supply terminal SYS_POWER (5V). Therefore, the second current flow direction of POWER_1 at this time is as follows: the conducting first controllable switch Q1 -> DC-DC module U1 -> first inductor L1 -> first unidirectional conduction module D1 -> the power supply system outputs the first voltage to the device power supply terminal SYS_POWER. The high potential at point A causes the gate (G) of the fifth controllable switch Q5 in the second control module 2 to be at a high level, thus controlling the fifth controllable switch Q5 to conduct. Since POWER_2 is not connected to voltage, there is no current in the relevant branches of POWER2. At this time, the third current flow of POWER_1 is as follows: resistor Rf7 -> control terminal of the fifth controllable switch Q5. The first voltage output will cause the potential at point B to be high. Due to the presence of the first unidirectional conduction module D1, the gate voltage of the third controllable switch Q3 is always greater than the source voltage (Vgs > 0). Therefore, the third controllable switch Q3 is always off, preventing voltage from flowing back from the device end SYS_POWER to POWER_2 through the third controllable switch Q3, and thus not affecting POWER_2. Therefore, the fourth current flow of POWER_1 is as follows: first controllable switch Q1 -> DC-DC module U1 -> first inductor L1 -> resistor R12 -> control terminal of the third controllable switch Q3.

[0069] The second operating state is when POWER_1 is not connected and POWER_2 is connected. When POWER_1 is not connected, the voltage level at point A is low, and the fifth controllable switch Q5 is off. When POWER_2 is connected, the gate (G) of the sixth controllable switch Q6 is high. POWER_2, after current limiting by resistors Rf5 and Rf6, controls the sixth controllable switch Q6 to conduct; this makes the gate (G) potential of the second controllable switch Q2 low, and Q2 conducts. Simultaneously, the third controllable switch Q3 contains a body diode, which is always conductive from drain to gate. Initially, there is a voltage drop through the body diode. After POWER_2 passes through the body diode, Vgs of Q3 is less than 0, Q3 is fully conductive, and the voltage drop is at its minimum. Therefore, POWER_2 is input to the device terminal SYS_POWER after passing through the third controllable switch Q3. Therefore, the first current flow of POWER_2 is: second controllable switch Q2 -> third controllable switch Q3 -> device terminal SYS_POWER. The second current flow of POWER_2 is: resistor Rf5 -> resistor Rf6 -> control terminal of the sixth controllable switch Q6. The third current flow of POWER_2 is: resistor Rx2 -> sixth controllable switch Q6 -> GND.

[0070] The third operating state occurs when POWER_1 is connected first, followed by POWER_2. When POWER_1 is connected, the potential at point A is high. The third current output from POWER_1 controls the fifth controllable switch Q5 to conduct. After POWER_2 is connected, the second current output from POWER_2 flows directly to GND through resistor Rf5 and the conducting fifth controllable switch Q5. The gate (G) level of the sixth controllable switch Q6 is low, therefore the sixth controllable switch Q6 is turned off. The third current output from POWER_2 then flows to the gate (G) of the second controllable switch Q2, making the gate potential of the second controllable switch Q2 high. The second controllable switch Q2 is turned off, thus breaking the first current loop of POWER_2. Therefore, only the main current loop of POWER_1 will continuously operate, outputting the first voltage to SYS_POWER. At this time, the current flow in the power supply circuit is: first controllable switch Q1 -> DC-DC module U1 -> first inductor L1 -> first unidirectional conduction module D1 -> device input SYS_POWER.

[0071] The fourth operating state is when both POWER_1 and POWER_2 are connected, and a switch from POWER_1 to POWER_2 is required. Based on the third operating state, POWER_1 is disconnected, the potential at point A is low, the fifth controllable switch Q5 is off, and the level at point B is pulled low. According to the second and third current outputs of POWER_2, the sixth controllable switch Q6 is turned on, the second controllable switch Q2 is turned on, and the first current loop corresponding to POWER_2 is turned on, thus achieving a switch to the second voltage output.

[0072] The fifth operating state occurs when both POWER_1 and POWER_2 are connected, and a switch from POWER_2 to POWER_1 is required. Building upon the fourth operating state, when POWER_1 is connected again, the potential at point A is pulled high, the fifth controllable switch Q5 turns on again, the sixth controllable switch Q6 turns off, and the second controllable switch Q2 turns off, disconnecting the first current loop of POWER_2. Simultaneously, the raised potential at point A controls the first controllable switch Q1 to turn on, thus switching to the first voltage output.

[0073] This invention provides a voltage switching circuit that can be implemented using only electronic components such as resistors, capacitors, and MOSFETs. Through ingenious design, it achieves fast, seamless, and smooth switching between power sources, ensuring smooth and continuous switching between multiple power sources and voltages. It can also immediately switch to the auxiliary power source when the main power fails, guaranteeing the normal operation of the power supply system. This results in a low-cost multi-power source coordinated power supply system that achieves anti-current backflow, zero voltage difference, and voltage-band soft start effects during power supply voltage switching, improving the flexibility of the voltage switching circuit and ensuring the safety and reliability of the entire circuit.

[0074] As an optional embodiment, it also includes:

[0075] The first energy storage module has its input end connected to the output end of the second control module 2 and its output end connected to the control end of the second controllable switch Q2. It is used to discharge when switching from the second voltage output to the first voltage output, so as to control the second controllable switch Q2 to conduct for a first preset time.

[0076] And / or,

[0077] The second energy storage module has its input terminals connected to the anode of the first unidirectional conduction module D1 and the second terminal of the first controllable switch Q1, respectively, and its output terminal connected to the control terminal of the third controllable switch Q3. It is used to discharge when switching from the second voltage output to the first voltage output, so as to control the third controllable switch Q3 to conduct for a second preset duration.

[0078] It's easy to understand that, to achieve a smooth switch between the two voltages, and considering that the first voltage, as the main power supply, operates for a relatively long time, the corresponding first circuit's conduction time will also be relatively long. Prolonged operation might lead to power loss during the first voltage's operation. Therefore, a first energy storage module and / or a second energy storage module can be added to the second circuit corresponding to the second voltage. When the second circuit outputs the second voltage, it charges both the first and second energy storage modules. When the voltage switching circuit needs to switch from outputting the second voltage to outputting the first voltage, if there is a brief power loss in the first voltage, the first and second energy storage modules will discharge, maintaining the corresponding second controllable switch Q2 and third controllable switch Q3 on for a first preset time or a second preset time. This allows the voltage switching circuit to output the second voltage to maintain the device's power supply during a brief power loss in the first voltage. Simultaneously, by using the first and second energy storage modules, the charging and discharging process of the energy storage modules ensures a smooth switch between the first and second voltage output states, compensating for energy loss during the switching gap. This application does not impose any special restrictions on the specific types and implementation methods of the first and second energy storage modules; they can be implemented using devices such as capacitors. The specific values ​​of the first and second preset durations can be set and adjusted according to actual application requirements, and this application does not impose any special restrictions on them.

[0079] Specifically, by setting up a first energy storage module and a second energy storage module, it is beneficial to achieve a fast, seamless, and smooth voltage switching process, ensuring a stable output of the power supply system when switching power supply voltage, so as to provide a continuous and reliable power supply voltage for the equipment, further ensuring the continuity of power supply, and improving the reliability of the entire voltage switching circuit and power supply system.

[0080] As an optional embodiment, the first energy storage module includes:

[0081] The first energy storage resistor R11 has its first end connected to the output end of the second control module 2;

[0082] The first energy storage capacitor C11 has its first end grounded, and its second end connected to the second end of the first energy storage resistor R11 and the control terminal of the second controllable switch Q2.

[0083] It is understood that the energy storage module can be implemented using a parallel connection of an energy storage resistor and an energy storage capacitor. Both the first and second energy storage modules can be implemented in this way. This embodiment uses the first energy storage module as an example to illustrate the connection relationship. The second energy storage module can be configured similarly, and this application will not repeat the details here. This application does not place any particular limitations on the specific type and implementation method of the first energy storage capacitor C11 and the first energy storage resistor R11. The first preset duration can be set and adjusted by adjusting the capacitance value of the first energy storage capacitor C11 and / or the resistance value of the first energy storage resistor R11. Figure 2 As shown, the second energy storage module is implemented using a second energy storage capacitor C12 and a second energy storage resistor R12 connected in parallel. The POWER_1 main current loop has a relatively long conduction time, which may lead to power loss. In this case, the first energy storage capacitor C11 discharges, and together with the first energy storage resistor R11, it keeps the second controllable switch Q2 conducting for a period of time. Simultaneously, the second energy storage capacitor C12 discharges, and together with the second energy storage resistor R12, it keeps the third controllable switch Q3 conducting for a period of time, ensuring that the system SYS_POWER can smoothly switch from the POWER_2 main current loop power supply to the POWER_1 current loop power supply, preventing SYS_POWER from losing power.

[0084] Specifically, the first energy storage module and / or the second energy storage module can be implemented by using capacitors and resistors connected in parallel. The structure is simple and easy to implement. The components used are low in cost and small in size, which is conducive to the simple implementation of the entire voltage switching circuit.

[0085] As an optional embodiment, it also includes:

[0086] The first soft-start module has its first end connected to the first end of the first controllable switch Q1, and its second end connected to the control end of the first controllable switch Q1.

[0087] And / or,

[0088] The second soft-start module has its first end connected to the first end of the second controllable switch Q2, and its second end connected to the control end of the second controllable switch Q2.

[0089] It is easy to understand that, to prevent voltage overshoot, a first soft-start module can be added to the first circuit and / or a second soft-start module can be added to the second circuit. When the first voltage is applied, the first soft-start module can control the voltage at the first terminal of the first controllable switch Q1 to gradually increase to the first voltage; when the second voltage is applied, the second soft-start module can control the voltage at the first terminal of the second controllable switch Q2 to gradually increase to the second voltage; thereby avoiding the impact of instantaneous surge current or large voltage on the voltage switching circuit when the first or second voltage is applied. This application does not specifically limit the specific types and implementation methods of the first and second soft-start modules. Figure 2 As shown, a slow-start module is implemented using a parallel connection of a slow-start resistor and a slow-start capacitor. In the first circuit, a slow-start resistor R21 and a slow-start capacitor C21 are connected in parallel to implement the first slow-start module. In the second circuit, a slow-start resistor R22 and a slow-start capacitor C22 are connected in parallel to implement the first slow-start module. Taking the first slow-start module as an example, due to the slow-start circuit formed by the slow-start resistor R21 and the slow-start capacitor C21, the subsequent circuit of the first controllable switch Q1 will maintain a low level during the time t=RC, and the first controllable switch Q1 will slowly conduct, forming a self-controlled slow-start circuit of POWER_1. Here, R is the resistance value of the slow-start resistor, and C is the capacitance value of the slow-start capacitor. Therefore, a suitable resistor and a suitable capacitor value can be selected according to the actual application requirements to implement the slow-start module, balancing startup efficiency and circuit safety. To ensure that the first energy storage module can be fully charged, the output terminal of the first energy storage module is also connected to the second terminal of the second slow-start module. When the second voltage is connected, the second voltage can directly charge the first energy storage module through the second slow-start module. Figure 2 As shown, the second voltage can charge the first energy storage capacitor C11 through the soft-start resistor R22.

[0090] Specifically, the gradual power-up of the power supply voltage is controlled by setting a soft-start module, thereby protecting the voltage switching circuit and ensuring the safety and reliability of the entire voltage switching circuit. The soft-start module can be implemented by combining resistors and capacitors, which is simple in structure, easy to implement, and uses low-cost and small-sized components, which is conducive to the simple implementation of the entire voltage switching circuit.

[0091] As an optional embodiment, it also includes:

[0092] The DCDC module U1 has its input terminal connected to the second terminal of the first controllable switch Q1, and is used to convert the first voltage into a preset voltage.

[0093] The first inductor L1 has its first terminal connected to the positive output terminal of the DC-DC module U1;

[0094] The first capacitor C1 has its first end connected to the second end of the first inductor L1, the anode of the first unidirectional conduction module D1, and the control terminal of the third controllable switch Q3, respectively. Its second end is grounded and connected to the negative output terminal of the DC-DC module U1.

[0095] It is understandable that, considering the possibility that the first voltage input in practical applications may differ from the voltage required by the device, a DC-DC (Direct Current to Direct Current) module can be added to the first circuit to convert the first voltage to the voltage required by the device. Simultaneously, a first inductor L1 connected in series and a first capacitor C1 connected in parallel are added to the output side of the DC-DC module U1. The first inductor L1 and the first capacitor C1 form an LC filter structure, which can suppress output voltage ripple, filter noise signals, stabilize current, improve dynamic response, and ensure that the quality of the output power meets the requirements, making the output of the DC-DC module U1 close to an ideal pure DC power supply. This application does not specifically limit the specific type and implementation method of the DC-DC module U1, the first inductor L1, and the first capacitor C1. The DC-DC module U1 can be implemented using a DC-DC chip, etc. The preset value of the converted voltage can be adjusted and set according to the device requirements in actual applications. When the second voltage differs from the device's required voltage, a similar setting can be made in the second circuit, which will not be elaborated upon here. Figure 2 As shown, PWRI is the input terminal of the DC-DC chip, GND1 is the ground terminal of the input side of the DC-DC chip, PWRO is the positive output terminal of the DC-DC chip, and GND2 is the positive output terminal of the DC-DC module.

[0096] Specifically, by setting up the DCDC module U1, it can be ensured that the output of the first circuit meets the DC power supply voltage required by the equipment, ensuring that the first circuit provides accurate and effective power supply to the equipment. The structure is simple and easy to implement, and the components used are low in cost and small in size, which is conducive to the simple implementation of the entire voltage switching circuit.

[0097] As an optional embodiment, it also includes one or more combinations of the first input capacitor C2, the second input capacitor C3, the first output capacitor C4, and the second output capacitor C5;

[0098] The first terminal of the first input capacitor C2 is grounded, the second terminal is connected to the first voltage, and is connected to the first terminal of the first controllable switch Q1;

[0099] The first terminal of the second input capacitor C3 is grounded, the second terminal is connected to the second voltage, and is connected to the first terminal of the second controllable switch Q2;

[0100] The first terminal of the first output capacitor C4 is grounded, and the second terminal is connected to the cathode of the first unidirectional conduction module D1.

[0101] The first terminal of the second output capacitor C5 is grounded, and the second terminal is connected to the second terminal of the third controllable switch Q3.

[0102] It is easy to understand that, in order to further improve the stability and reliability of the output voltage, input capacitors at the input end and output capacitors at the output end can be set in the first circuit and / or the second circuit. The first input capacitor C2 is set at the input end of the first circuit, and the second input capacitor C3 is set at the input end of the second circuit. These capacitors can suppress fluctuations in the input first voltage, acting as filters, absorbing interference signals, and preventing interference signals from affecting the downstream circuits. They can also store energy when the corresponding voltage is applied, achieving delayed power-on. The first output capacitor C4 is set at the output end of the first circuit, and the second output capacitor C5 is set at the output end of the second circuit. These capacitors can smooth the voltage ripple of the final output voltage, acting as filters, stabilizing the output voltage, and ensuring that the device receives a stable DC voltage. When the first voltage and / or the second voltage is abnormal, the energy stored in the output capacitors can also maintain the device's operation for a short time, providing a buffer time. This application does not specifically limit the specific types and implementation methods of the first input capacitor C2, the second input capacitor C3, the first output capacitor C4, and the second output capacitor C5.

[0103] Furthermore, a series-connected pre-amplifier circuit can be added to the output terminals of the first voltage and / or the second voltage, i.e., the input terminals of the first circuit and / or the second circuit. The pre-amplifier circuit includes one or more combinations of a series-connected fuse, a parallel-connected grounding capacitor, a series-connected resistor, and a diode with its anode grounded. The pre-amplifier circuit can perform filtering, reverse connection protection, and other functions, providing preliminary processing of the input first or second voltage and further protecting the circuit. Figure 2 As shown, a series-connected preamplifier circuit is added to the input terminal of the first circuit.

[0104] Specifically, by setting the input and output capacitors, the accuracy and reliability of the final output voltage to the device can be further guaranteed. The structure is simple and easy to implement, and the components used are low-cost and small in size, which is conducive to the simple implementation of the entire voltage switching circuit.

[0105] As an optional embodiment, the first control module 1 includes:

[0106] The first voltage divider circuit has its first terminal connected to the control terminal of the first controllable switch Q1, and its voltage divider terminal connected to the first terminal of the first controllable switch Q1.

[0107] The fourth controllable switch Q4 has a control terminal for connecting to the first voltage, a first terminal grounded, and a second terminal connected to the second terminal of the first voltage divider circuit. It is used to conduct when the first voltage is connected, so as to cooperate with the first voltage divider circuit to control the first controllable switch Q1 to conduct, and to turn off when the first voltage is not connected, so as to cooperate with the first voltage divider circuit to control the first controllable switch Q1 to turn off.

[0108] It is understood that the first control module 1 can be implemented using a circuit built with switching devices. The control terminal of the fourth controllable switch Q4 is connected to the first voltage, and is directly turned on or off under the control of the first voltage. Simultaneously, its second terminal is connected to the control terminal of the first controllable switch Q1 through the first voltage divider circuit. By turning on or off, it controls whether the control terminal of the first controllable switch Q1 is pulled low, thereby controlling the first controllable switch Q1. The voltage at the second terminal of the fourth controllable switch Q4 is reduced using the first voltage divider circuit, thus reducing circuit power consumption. Specifically, the voltage divider terminal of the first voltage divider circuit can be connected to the first terminal of the first controllable switch Q1 through the first soft-start module. When the fourth controllable switch Q4 is off, the soft-start switch in the first soft-start module further ensures that the voltage between the control terminal and the first terminal of the first controllable switch Q1 is equal, ensuring that the first controllable switch Q1 is off when the fourth controllable switch Q4 is off. This application does not specifically limit the specific type and implementation method of the fourth controllable switch Q4 and the first voltage divider circuit. Figure 2 As shown, the fourth controllable switch Q4 can be implemented using an NMOS transistor, and the first voltage divider circuit is implemented using voltage divider resistors Rf1 and Rf2 connected in series. The connection point of the two resistors in series serves as the voltage divider terminal of the first voltage divider circuit.

[0109] Specifically, the first control module 1 can be implemented using the fourth controllable switch Q4, especially using a MOSFET. It requires only a very small drive current to achieve control, has low dynamic drive loss, fast switching speed, no need for complex bias circuits, simple structure, easy to implement, and uses low-cost and small-sized components, which is conducive to the simple implementation of the entire voltage switching circuit.

[0110] As an optional embodiment, the first control module 1 further includes:

[0111] The second voltage divider circuit has a first terminal for connecting to the first voltage, a second terminal for grounding, and the voltage divider terminal connected to the control terminal of the fourth controllable switch Q4.

[0112] And / or,

[0113] The first current limiting module Rx1 has its first terminal connected to the output terminal of the second voltage divider circuit, and its second terminal connected to the control terminal of the fourth controllable switch Q4.

[0114] It is easy to understand that, to avoid the impact of the first voltage on the control terminal of the fourth controllable switch Q4, a first current-limiting module Rx1 and / or a second voltage divider circuit can be added to the control terminal of the fourth controllable switch Q4. The first voltage will first be divided by the second voltage divider circuit, and the divided voltage can be further divided by the first current-limiting module Rx1 before being output to the control terminal of the fourth controllable switch Q4. Through voltage division and / or current limiting, a direct connection between the first voltage and the control terminal of the fourth controllable switch Q4 is avoided, thereby preventing the first voltage from impacting the control terminal of the fourth controllable switch Q4 and protecting the circuit. The second voltage divider circuit reduces the voltage at the control terminal of the fourth controllable switch Q4, reducing circuit power consumption. This application does not specifically limit the specific type and implementation method of the first current-limiting module Rx1 and the second voltage divider circuit. Figure 2 As shown, the first current limiting module Rx1 is implemented using a resistor, and the second voltage divider circuit is implemented using voltage divider resistors Rf3 and Rf4 connected in series. The connection point of the two resistors in series serves as the voltage divider terminal of the second voltage divider circuit.

[0115] Specifically, by setting the first current limiting module Rx1 and / or the second voltage divider circuit, the fourth controllable switch Q4 can be effectively protected, damage to the fourth controllable switch Q4 can be avoided, the service life of the voltage switching circuit can be improved, and the safety and reliability of the voltage switching circuit can be guaranteed. The structure is simple and easy to implement, and the components used are low in cost and small in size, which is conducive to the simple implementation of the entire voltage switching circuit.

[0116] As an optional embodiment, the second control module 2 includes:

[0117] The second current limiting module Rx2 has its first terminal used to connect to the second voltage.

[0118] The fifth controllable switch Q5 has a control terminal for connecting to the first voltage and a first terminal for grounding. It is used to turn on when the first voltage is connected and turn off when the first voltage is not connected.

[0119] The sixth controllable switch Q6 has its control terminal connected to the second terminal of the fifth controllable switch Q5 and is connected to the second voltage. Its first terminal is grounded, and its second terminal is connected to the second terminal of the second current limiting module Rx2 and the control terminal of the second controllable switch Q2. It is used to turn off when the fifth controllable switch Q5 is on or the second voltage is not connected, so as to control the second controllable switch Q2 to turn off. When the fifth controllable switch Q5 is off and the second voltage is connected, it is turned on, so as to control the second controllable switch Q2 to turn on.

[0120] It is understood that the second control module 2 can be implemented using a circuit built with switching devices. Specifically, the second control module 2 includes a two-stage control structure consisting of a fifth controllable switch Q5 and a sixth controllable switch Q6. The control terminal of the fifth controllable switch Q5 is connected to a first voltage, and is directly turned on or off under the control of the first voltage. Simultaneously, the on / off state of the fifth controllable switch Q5 and the connection of the second voltage will affect the control terminal of the sixth controllable switch Q6, achieving switching control between the two voltages through the on / off state of the sixth controllable switch Q6. Furthermore, to avoid the impact of the second voltage on the control terminal of the second controllable switch Q2, a second current-limiting module Rx2 can be added in series between the second voltage and the control terminals of the second controllable switch Q2, which can also protect the second terminal of the sixth controllable switch Q6. This application does not specifically limit the specific types and implementation methods of the second current-limiting module Rx2, the fifth controllable switch Q5, and the sixth controllable switch Q6. Figure 2 As shown, the fifth controllable switch Q5 and the sixth controllable switch Q6 can be implemented using NMOS, and the second current limiting module Rx2 is implemented using a series resistor element. The second current limiting module Rx2 can further form a voltage divider circuit with the first energy storage resistor R11 in the first energy storage module.

[0121] Specifically, the second control module 2 can be implemented using the fifth controllable switch Q5 and the sixth controllable switch Q6. The two-stage control structure enables accurate control of the second controllable switch Q2. The structure is simple and easy to implement. The components used are low-cost and small in size, which is conducive to the simple implementation of the entire voltage switching circuit.

[0122] As an optional embodiment, the second control module 2 further includes:

[0123] The third voltage divider circuit has a first terminal connected to the second voltage, a second terminal connected to the control terminal of the sixth controllable switch Q6, and a voltage divider terminal connected to the second terminal of the fifth controllable switch Q5.

[0124] And / or,

[0125] The fourth voltage divider circuit has a first voltage connected to its first terminal, a grounded second terminal, and the voltage divider terminal connected to the control terminal of the fifth controllable switch Q5.

[0126] It is easy to understand that, to further protect the circuit, a third voltage divider circuit can be added between the control terminal of the sixth controllable switch Q6 and the second voltage, and / or a fourth voltage divider circuit can be added between the control terminal of the fifth controllable switch Q5 and the first voltage. These voltage divider circuits prevent the first voltage from impacting the fifth controllable switch Q5 and the second voltage from impacting the sixth controllable switch Q6. Simultaneously, a parallel capacitor can be added between the dividing terminal and the second terminal of the fourth voltage divider circuit to stabilize the voltage output to the control terminal of the fifth controllable switch Q5, filter out noise signals, prevent interference signals from causing malfunctions of the fifth controllable switch Q5, and further optimize switching losses. This application does not specifically limit the specific types and implementation methods of the third and fourth voltage divider circuits. Figure 2 As shown, a third voltage divider circuit can be implemented using series-connected voltage divider resistors Rf5 and Rf6, with the series connection point of the two resistors serving as the voltage divider terminal. A fourth voltage divider circuit can be implemented using series-connected voltage divider resistors Rf7 and Rf8, with the series connection point of the two resistors serving as the voltage divider terminal. A capacitor C6 is connected in parallel across voltage divider resistor Rf8. By utilizing the current-limiting module and the voltage divider circuit, the voltage at some connection points in the circuit is reduced, thereby reducing circuit power consumption.

[0127] As a specific embodiment, such as Figure 2 As shown, the entire voltage switching circuit only requires surface-mount diodes, surface-mount resistors, surface-mount PMOS / NMOS transistors, and surface-mount capacitors. The package size, capacitance, and other parameters of the capacitors, as well as the number of capacitors, voltage, soft-start time, and energy storage, can be set and adjusted according to application requirements. The number of capacitors can be adjusted based on the area of ​​the power-down curve. When the first unidirectional conduction module D1 is implemented using a diode, the pn junction voltage drop, temperature curve, and package size of the diode can be determined based on the actual voltage magnitude. The parameters of each PMOS or NMOS transistor in the circuit, such as Vds, Vgs, Id, Idm, Pw, volt-ampere characteristic curves, and package size, can be selected according to actual application requirements and the magnitude of the corresponding first and second voltages. The entire circuit includes 3 PMOS transistors, 3 NMOS transistors, 13 resistors, and 9 capacitors. It has a simple structure, low cost, fast switching speed, small switching level fluctuation, and can stably perform fast, continuous, and zero-dropout switching between POWER_1 and POWER_2.

[0128] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0129] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A voltage switching circuit, characterized in that, include: The first controllable switch has a first terminal for connecting to a first voltage and a second terminal for outputting the first voltage. The first control module has an input terminal for receiving the first voltage and an output terminal connected to the control terminal of the first controllable switch. It is used to control the first controllable switch to be turned on when the first voltage is connected and to control the first controllable switch to be turned off when the first voltage is not connected. The second controllable switch has a first terminal for connecting to the second voltage and a second terminal for outputting the second voltage. The second control module has an input terminal for receiving the first voltage and the second voltage, and an output terminal connected to the control terminal of the second controllable switch. It is used to control the second controllable switch to be turned on when the second voltage is turned on and the first voltage is not turned on, and to control the second controllable switch to be turned off when the second voltage is not turned on or the first voltage is turned on.

2. The voltage switching circuit according to claim 1, characterized in that, Also includes: The first unidirectional conduction module has its anode connected to the second terminal of the first controllable switch, and its cathode serving as the output terminal of the first voltage. And / or, The third controllable switch has its control terminal connected to the anode of the first unidirectional conduction module and the second terminal of the first controllable switch, and its first terminal connected to the second terminal of the second controllable switch. The second terminal serves as the output terminal of the second voltage, and is used to turn off when the first voltage is turned on and turn on when the first voltage is not turned on.

3. The voltage switching circuit according to claim 2, characterized in that, Also includes: The first energy storage module has its input end connected to the output end of the second control module and its output end connected to the control end of the second controllable switch. It is used to discharge when switching from the second voltage output to the first voltage output, so as to control the second controllable switch to conduct for a first preset duration. And / or, The second energy storage module has its input terminal connected to the anode of the first unidirectional conduction module and the second terminal of the first controllable switch, respectively, and its output terminal connected to the control terminal of the third controllable switch. It is used to discharge when switching from the second voltage output to the first voltage output, so as to control the third controllable switch to conduct for a second preset duration.

4. The voltage switching circuit according to claim 3, characterized in that, The first energy storage module includes: The first energy storage resistor has its first end connected to the output end of the second control module; The first energy storage capacitor has its first end grounded, and its second end connected to the second end of the first energy storage resistor and the control terminal of the second controllable switch, respectively.

5. The voltage switching circuit according to claim 1, characterized in that, Also includes: The first soft-start module has a first end connected to the first end of the first controllable switch and a second end connected to the control end of the first controllable switch. And / or, The second soft-start module has a first end connected to the first end of the second controllable switch and a second end connected to the control end of the second controllable switch.

6. The voltage switching circuit according to claim 2, characterized in that, Also includes: The DCDC module has its input terminal connected to the second terminal of the first controllable switch, and is used to convert the first voltage into a voltage of a preset magnitude. The first inductor has its first end connected to the positive output terminal of the DC-DC module; The first capacitor has its first end connected to the second end of the first inductor, the anode of the first unidirectional conduction module, and the control terminal of the third controllable switch, respectively. Its second end is grounded and connected to the negative output terminal of the DC-DC module.

7. The voltage switching circuit according to claim 2, characterized in that, It also includes one or more combinations of a first input capacitor, a second input capacitor, a first output capacitor, and a second output capacitor; The first terminal of the first input capacitor is grounded, the second terminal is connected to the first voltage, and is connected to the first terminal of the first controllable switch; The first terminal of the second input capacitor is grounded, the second terminal is connected to the second voltage, and is connected to the first terminal of the second controllable switch; The first terminal of the first output capacitor is grounded, and the second terminal is connected to the cathode of the first unidirectional conduction module; The first terminal of the second output capacitor is grounded, and the second terminal is connected to the second terminal of the third controllable switch.

8. The voltage switching circuit according to any one of claims 1 to 7, characterized in that, The first control module includes: The first voltage divider circuit has its first terminal connected to the control terminal of the first controllable switch, and its voltage divider terminal connected to the first terminal of the first controllable switch. The fourth controllable switch has a control terminal for connecting to the first voltage, a first terminal grounded, and a second terminal connected to the second terminal of the first voltage divider circuit. It is used to conduct when the first voltage is connected, so as to cooperate with the first voltage divider circuit to control the first controllable switch to conduct, and to turn off when the first voltage is not connected, so as to cooperate with the first voltage divider circuit to control the first controllable switch to turn off.

9. The voltage switching circuit according to claim 8, characterized in that, The first control module further includes: The second voltage divider circuit has a first terminal for connecting to the first voltage, a second terminal for grounding, and a voltage divider terminal connected to the control terminal of the fourth controllable switch. And / or, The first current limiting module has its first end connected to the output end of the second voltage divider circuit, and its second end connected to the control end of the fourth controllable switch.

10. The voltage switching circuit according to any one of claims 1 to 7, characterized in that, The second control module includes: The second current limiting module has its first terminal used to connect to the second voltage. The fifth controllable switch has a control terminal for connecting to the first voltage and a first terminal for grounding. It is used to turn on when the first voltage is connected and turn off when the first voltage is not connected. The sixth controllable switch has its control terminal connected to the second terminal of the fifth controllable switch and connected to the second voltage. Its first terminal is grounded, and its second terminal is connected to the second terminal of the second current limiting module and the control terminal of the second controllable switch, respectively. It is used to turn off when the fifth controllable switch is on or when the second voltage is not connected, so as to control the second controllable switch to turn off. When the fifth controllable switch is off and the second voltage is connected, it is turned on, so as to control the second controllable switch to turn on.

11. The voltage switching circuit according to claim 10, characterized in that, The second control module also includes: The third voltage divider circuit has the second voltage connected to its first terminal, the control terminal of the sixth controllable switch connected to its second terminal, and the voltage divider terminal connected to the second terminal of the fifth controllable switch. And / or, The fourth voltage divider circuit has the first terminal connected to the first voltage, the second terminal grounded, and the voltage divider terminal connected to the control terminal of the fifth controllable switch.

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